Two-stage optical isolator

Abstract

The utility model discloses a two-stage optical isolator, and relates to the technical field of optical equipment. The two-stage optical isolator comprises a first polarizing beam splitter, a first optical rotation assembly, a second polarizing beam splitter, a second optical rotation assembly and a third polarizing beam splitter which are sequentially arranged in the direction of an optical path, and a light beam is split into a P-polarized light beam and an S-polarized light beam through the first polarizing beam splitter and then is emitted in parallel; the P polarized light beam and the S polarized light beam are emitted after being rotated by 90 degrees through the first optical rotation assembly, then penetrate through the second polarization beam splitter and then sequentially pass through the second optical rotation assembly and the third polarization beam splitter to be combined and emitted, and the second optical rotation assembly rotates the reversely-entering light beam by 90 degrees. The whole structure can be simplified, and the product percent of pass is improved.

Description

Technical Field

[0001] This application relates to the field of optical equipment technology, and more specifically, to a two-stage optical isolator. Background Technology

[0002] An optical isolator is a passive optical device that allows only unidirectional light to pass through. Its working principle is based on the non-reciprocity of Faraday rotation; light reflected back from the optical fiber can be effectively isolated by the isolator. Two-stage optical isolators offer superior temperature performance, a wider bandwidth range, and higher isolation compared to single-stage optical isolators.

[0003] In the existing technology, both the first and second stage isolators of a two-stage optical isolator have birefringent crystals, which makes the structure relatively complex, difficult to assemble, and affects the product qualification rate. Utility Model Content

[0004] The purpose of this application is to provide a two-stage optical isolator that simplifies the overall structure and improves the product qualification rate.

[0005] The embodiments of this application are implemented as follows:

[0006] This application provides a two-stage optical isolator, including a first polarizing beam splitter, a first optical rotator, a second polarizing beam splitter, a second optical rotator, and a third polarizing beam splitter arranged sequentially along the optical path. The light beam is split into a P-polarized beam and an S-polarized beam by the first polarizing beam splitter and then emitted in parallel. The P-polarized beam and the S-polarized beam are rotated by 90° by the first optical rotator and then emitted. Subsequently, after passing through the second polarizing beam splitter, they are sequentially passed through the second optical rotator and the third polarizing beam splitter and then merged before being emitted. The second optical rotator rotates the beam entering in the opposite direction by 90°.

[0007] Optionally, as an implementable method, the first polarizing beam splitter has a first beam splitter and a second beam splitter arranged parallel to each other. The transmission axis of the first beam splitter and the second beam splitter are both S-axis. The S-polarized beam can pass through the first beam splitter and then exit. The P-polarized beam is reflected by the first beam splitter and the second beam splitter in sequence and then exits parallel to the P-polarized beam.

[0008] Optionally, as an implementable method, the angle between the first beam splitter, the second beam splitter, and the incident light beam is 45°.

[0009] Optionally, as an implementable method, the second polarizing beam splitter has a third beam splitter and a fourth beam splitter arranged perpendicularly to each other, wherein the transmission axis of the third beam splitter is the P-axis and the transmission axis of the fourth beam splitter is the S-axis.

[0010] Alternatively, as an implementable method, the third beam splitter is parallel to the first beam splitter.

[0011] Optionally, as an implementable method, the third polarizing beam splitter has a fifth beam splitter and a sixth beam splitter arranged parallel to each other, the transmission axis of the fifth beam splitter and the sixth beam splitter being the S-axis, the S-polarized beam can pass through the sixth beam splitter, and the P-polarized beam passes through the fifth beam splitter and the sixth beam splitter in sequence and merges with the S-polarized beam before exiting.

[0012] Optionally, as an implementable method, the angle between the fifth beam splitter, the sixth beam splitter and the incident light beam is 45°.

[0013] Optionally, as an implementable method, the first optical rotation component includes a first optical rotator and a first magneto-optical crystal arranged sequentially along the optical path direction. A first magnet is disposed on the outside of the first magneto-optical crystal. The P-polarized beam and the S-polarized beam are rotated and interchanged by passing through the first optical rotator and the first magneto-optical crystal in sequence.

[0014] Optionally, as an implementable method, the second optical rotation component includes a second magneto-optical crystal and a second optical rotation plate arranged sequentially along the optical path direction. A second magnet is disposed on the outside of the second magneto-optical crystal. The P-polarized beam and the S-polarized beam incident in opposite directions are rotated and interchanged by the second magneto-optical crystal and the second optical rotation plate in sequence.

[0015] Optionally, as an implementable approach, it also includes a collimator disposed at the incident light level, through which the light beam is first collimated and emitted to the first polarizing beam splitter.

[0016] The beneficial effects of the embodiments of this application include:

[0017] The two-stage optical isolator provided in this application includes a first polarizing beam splitter, a first optical rotator, a second polarizing beam splitter, a second optical rotator, and a third polarizing beam splitter arranged sequentially along the optical path. The light beam is split into a P-polarized beam and an S-polarized beam by the first polarizing beam splitter and then exits in parallel. The P-polarized beam and the S-polarized beam are rotated 90° by the first optical rotator before exiting. They then pass through the second polarizing beam splitter and subsequently through the second optical rotator and the third polarizing beam splitter, merging before exiting. The second optical rotator rotates the beam entering in the opposite direction by 90°. Compared to the complex structure of traditional two-stage optical isolators that all use birefringent crystals, this application only uses a combination of polarizing beam splitters and optical rotators, reducing the reliance on high-precision birefringent crystals and greatly simplifying the overall structure. The relative reduction in the number of components and the simplification of the structure make it easier for operators to master the assembly process during production and assembly, reducing the probability of errors caused by complex component connections. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a two-stage optical isolator provided in an embodiment of this application;

[0020] Figure 2 This is one of the optical path diagrams of a two-stage optical isolator provided in the embodiments of this application;

[0021] Figure 3 The second optical path diagram of the two-stage optical isolator provided in the embodiments of this application.

[0022] Icons: 100-Dual-stage optical isolator; 110-First polarizing beam splitter; 111-First beam splitter film; 112-Second beam splitter film; 120-First optical rotation component; 121-First optical rotation plate; 122-First magneto-optical crystal; 123-First magnet; 130-Second polarizing beam splitter; 131-Third beam splitter film; 132-Fourth beam splitter film; 140-Second optical rotation component; 141-Second optical rotation plate; 142-Second magneto-optical crystal; 143-Second magnet; 150-Third polarizing beam splitter; 151-Fifth beam splitter film; 152-Sixth beam splitter film; 160-Collider. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0025] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] Please refer to Figure 1 , Figure 2 and Figure 3 This embodiment provides a two-stage optical isolator 100, including a first polarizing beam splitter 110, a first optical rotator 120, a second polarizing beam splitter 130, a second optical rotator 140, and a third polarizing beam splitter 150 arranged sequentially along the optical path. The light beam is split into a P-polarized beam and an S-polarized beam by the first polarizing beam splitter 110 and then emitted in parallel. The P-polarized beam and the S-polarized beam are rotated by the first optical rotator 120° and then emitted. After passing through the second polarizing beam splitter 130, they are sequentially passed through the second optical rotator 140 and the third polarizing beam splitter 150 and then merged before being emitted. The second optical rotator 140 rotates the beam entering in the opposite direction by 90°.

[0028] When the light beam enters the first polarizing beam splitter 110, based on the principle of polarization beam splitting, the beam is precisely split into a P-polarized beam and an S-polarized beam, and these two beams exit in parallel. Subsequently, the P-polarized beam and the S-polarized beam enter the first optical rotator 120. Inside this component, through special material and structural design, the polarization direction of the beam is precisely rotated 90° before exiting. The rotated beam then reaches the second polarizing beam splitter 130. At this point, due to the change in polarization state and the characteristics of the second polarizing beam splitter 130, the beam can pass through smoothly. The beam passing through the second polarizing beam splitter 130 continues forward, passing sequentially through the second optical rotator 140 and the third polarizing beam splitter 150. The second optical rotator 140 is particularly crucial; when a beam enters in the opposite direction, it can rotate it 90°, changing the polarization state of the reverse beam, thus preventing the reverse beam from returning along its original optical path, achieving a highly efficient optical isolation effect. Finally, after a series of processing steps, the forward-transmitting beams are combined and emitted at the third polarizing beam splitter 150, completing the entire forward transmission process of the optical signal.

[0029] The reversed light first enters the third polarizing beam splitter 150 and is split into a P-polarized beam and an S-polarized beam. The P-polarized beam and the S-polarized beam are incident parallel to each other onto the second optical rotator 140, rotating the polarization state of the reversed light by 90°. The rotated reversed light reaches the second polarizing beam splitter 130. Since its polarization state is completely different from the polarization state required for forward transmission, it cannot pass through the second polarizing beam splitter 130 and is reflected in other directions, thus achieving effective isolation of the reversed light and ensuring that the forward optical path is not interfered with by the reversed light.

[0030] The dual-stage optical isolator 100 provided in this application includes a first polarizing beam splitter 110, a first optical rotator 120, a second polarizing beam splitter 130, a second optical rotator 140, and a third polarizing beam splitter 150 arranged sequentially along the optical path. The light beam is split into a P-polarized beam and an S-polarized beam by the first polarizing beam splitter 110 and then emitted in parallel. The P-polarized beam and the S-polarized beam are rotated 120° by the first optical rotator 120 before being emitted. They then pass through the second polarizing beam splitter 130 and subsequently through the second optical rotator 140 and the third polarizing beam splitter 150 before merging and emitting the beam. The second optical rotator 140 rotates the beam entering in the opposite direction by 90°. Compared to the complex structure of traditional dual-stage optical isolators 100 that all employ birefringent crystals, this application uses only a combination of polarizing beam splitters and optical rotators, reducing the reliance on high-precision birefringent crystals and greatly simplifying the overall structure. The relative reduction in the number of parts and the simplification of the structure make it easier for operators to master the assembly process during production and assembly, reducing the probability of errors caused by complex connections between parts.

[0031] Furthermore, it also includes a collimator 160 set in the incident light meter, through which the light beam is first collimated and emitted to the first polarizing beam splitter 110.

[0032] In one possible embodiment of this application, such as Figure 1 , Figure 2 and Figure 3As shown, the first polarizing beam splitter 110 has a first beam-splitting film 111 and a second beam-splitting film 112 arranged parallel to each other. An S-polarized beam can pass through the first beam-splitting film 111 and exit, while a P-polarized beam is reflected sequentially by the first and second beam-splitting films 111 and exits parallel to the P-polarized beam. This unique double-layer film structure is key to achieving precise beam splitting. When a beam is incident on the first polarizing beam splitter 110, due to the differences in the interaction characteristics between different polarization states of light and the film layers, the S-polarized beam can pass through the first beam-splitting film 111 and exit smoothly, while the P-polarized beam is reflected sequentially by the first beam-splitting film 111 and reaches the second beam-splitting film 112, where it is reflected again and finally exits parallel to the S-polarized beam that passed through the first beam-splitting film 111. This design ensures that the incident beam is precisely split into two parallel beams with clearly defined polarization states from the outset, laying a solid foundation for subsequent optical signal processing and enabling the entire optical isolator to operate efficiently according to the predetermined optical path logic.

[0033] In one possible embodiment of this application, such as Figure 1 , Figure 2 and Figure 3 As shown, the angle between the first beam splitter 111, the second beam splitter 112, and the incident light beam is 45°. This 45° angle allows for optimal energy distribution and optical path reversal of the P-polarized and S-polarized beams during the beam splitting process by the first polarizing beam splitter 110. For the S-polarized beam, incident at 45° onto the first beam splitter 111, the transmittance requirement is met while maintaining the regularity of the outgoing direction. For the P-polarized beam, two 45° reflections (passing through the first beam splitter 111 and the second beam splitter 112 sequentially) precisely change its propagation direction to be parallel to the S-polarized beam, maximizing the utilization of light energy and minimizing unnecessary reflection losses.

[0034] In one possible embodiment of this application, such as Figure 1 , Figure 2 and Figure 3As shown, the second polarizing beam splitter 130 has a third beam splitter 131 and a fourth beam splitter 132 arranged perpendicularly to each other. P-polarized beams can pass through the third beam splitter 131, and S-polarized beams can pass through the fourth beam splitter 132. When the optical signal reaches the second polarizing beam splitter 130 after being rotated 90° by the first optical rotator 120, the polarization states of the P-polarized and S-polarized beams have changed. At this time, the vertical arrangement of the third and fourth beam splitters 131 allows for targeted filtering. The P-polarized beam can pass smoothly based on its optical interaction with the third beam splitter 131, while the S-polarized beam is adapted to the fourth beam splitter 132 and can pass through. This ensures that the beam processed by the first optical rotator 120 can pass through the second polarizing beam splitter 130 in an orderly manner and continue along the predetermined optical path, creating conditions for further processing of the subsequent optical signal.

[0035] It should be noted that the second polarizing beam splitter 130 includes two components: a second polarizing beam splitter 130 with a third beam splitter film 131 and a second polarizing beam splitter 130 with a fourth beam splitter film 132. The transmission axes of the second polarizing beam splitter 130 with the third beam splitter film 131 are different; the transmission axis of the second polarizing beam splitter 130 with the third beam splitter film 131 is the P-axis, and the transmission axis of the second polarizing beam splitter 130 with the fourth beam splitter film 132 is the S-axis. In one feasible embodiment of this application, as... Figure 1 , Figure 2 and Figure 3 As shown, the third beam-splitting film 131 is parallel to the first beam-splitting film 111. After the optical signal is split by the first polarizing beam splitter 110 and undergoes polarization state conversion by the first optical rotation component 120, when it reaches the second polarizing beam splitter 130, the parallelism of the third beam-splitting film 131 ensures that the optical signal can still interact with the film layers based on similar optical principles after undergoing numerous processing stages. For P-polarized beams, reflection occurs at the first polarizing beam splitter 110 according to the characteristics of the first beam-splitting film 111. Upon reaching the second polarizing beam splitter 130, facing the parallel third beam-splitting film 131, it can smoothly pass through as expected. Similarly, the transmission behavior of S-polarized beams in the corresponding film layers remains consistent. This parallel design greatly simplifies the complexities of optical path design, making the optical path logic of the entire optical isolator clearer, easier to understand, and easier to implement and control.

[0036] In one possible embodiment of this application, such as Figure 1 , Figure 2 and Figure 3As shown, the first polarizing beam splitter 110 has a fifth beam splitter 151 and a sixth beam splitter 152 arranged parallel to each other. The S-polarized beam can pass through the sixth beam splitter 152, while the P-polarized beam passes through the fifth beam splitter 151 and the sixth beam splitter 152 in sequence and is then merged with the S-polarized beam before exiting. In the forward optical path, after the beam is split by the first polarizing beam splitter 110, rotated by the first optical rotator 120, filtered by the second polarizing beam splitter 130, and processed by the second optical rotator 140, the beams of different polarization states need to be recombined into a complete optical signal output. At this time, the S-polarized beam can pass through due to its optical properties and those of the sixth beam splitter 152, while the P-polarized beam passes through the fifth beam splitter 151 and the sixth beam splitter 152 in sequence. Through multiple reflections and refractions, it is finally merged with the S-polarized beam before exiting, completing the entire process of optical signal separation, processing, and final merging output, ensuring that the optical isolator can provide a stable and single optical signal to the subsequent optical communication system.

[0037] In one possible embodiment of this application, such as Figure 1 , Figure 2 and Figure 3 As shown, the fifth beam splitter 151 and the sixth beam splitter 152 form an angle of 45° with the incident beam. When the beam, after being processed by the preceding series of optical path components, arrives at the third polarizing beam splitter 150 with a specific polarization state and direction, the 45° angle ensures that the P-polarized beam and the S-polarized beam follow the most ideal energy distribution and optical path steering rules during their interaction with the fifth beam splitter 151 and the sixth beam splitter 152. For the S-polarized beam, being incident at 45° onto the sixth beam splitter 152 guarantees both appropriate transmittance and that the exit direction meets the final merging requirements. For the P-polarized beam, two 45° reflections (passing through the fifth beam splitter 151 and the sixth beam splitter 152 successively) precisely adjust its propagation direction, allowing it to perfectly merge with the S-polarized beam under optimal energy utilization, maximizing the quality of the optical signal output.

[0038] In one possible embodiment of this application, such as Figure 1 , Figure 2 and Figure 3As shown, the first optical rotator 120 includes a first optical rotator 121 and a first magneto-optical crystal 122 arranged sequentially along the optical path. A first magnet 123 is disposed on the outer side of the first magneto-optical crystal 122. P-polarized beams and S-polarized beams are rotated and swapped sequentially by passing through the first optical rotator 121 and the first magneto-optical crystal 122. When the beam enters the first optical rotator 120 from the first polarizing beam splitter 110 as parallel P-polarized and S-polarized beams, it first passes through the first optical rotator 121, which plays a role in initially adjusting the polarization characteristics of the beam, laying the groundwork for the efficient operation of the subsequent magneto-optical crystal. Then, the beam enters the first magneto-optical crystal 122. Under the influence of the magnetic field generated by the first magnet 123, the polarization direction of the beam rotates based on the Faraday rotation effect, so that the polarization states of the original P-polarized and S-polarized beams are precisely swapped. This provides a key polarization state basis for optical signal processing in the subsequent optical path, ensuring that the optical isolator can continuously advance optical signal transmission according to the predetermined optical path logic.

[0039] In one possible embodiment of this application, such as Figure 1 , Figure 2 and Figure 3 Figure 1 Figure 2 Figure 3 As shown, the second optical rotator 140 includes a second magneto-optical crystal 142 and a second optical rotator 141 arranged sequentially along the optical path. A second magnet 143 is disposed on the outer side of the second magneto-optical crystal 142. The reverse-incident P-polarized beam and S-polarized beam are rotated and interchanged sequentially by the second magneto-optical crystal 142 and the second optical rotator 141. This structure plays a crucial role in handling reverse-incident beams. When reverse light attempts to enter the optical isolator and reaches the second optical rotator 140 after being decomposed by the third polarizing beam splitter 150, the second magneto-optical crystal 142, under the influence of the magnetic field generated by the second magnet 143, rotates the reverse-incident P-polarized beam and S-polarized beam by 90° according to the Faraday rotation effect, initially changing their polarization states. Subsequently, the second optical rotator 141 further optimizes and adjusts the polarization characteristics of the beam, completely changing the polarization state of the reverse light, preventing it from returning along the original optical path, thus achieving a highly efficient optical isolation effect. This structural design ensures smooth transmission of the forward optical path while strongly blocking interference from the reverse light, providing solid support for the bidirectional optical characteristic control of the optical isolator.

[0040] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A two-stage optical isolator, characterized by, The first polarizing beamsplitter, the first rotatory component, the second polarizing beamsplitter, the second rotatory component and the third polarizing beamsplitter are sequentially arranged along the light path direction, the light beam is divided into P-polarized light beam and S-polarized light beam after passing through the first polarizing beamsplitter and then parallelly exits, the P-polarized light beam and the S-polarized light beam rotate 90° after passing through the first rotatory component and then exit, and then pass through the second polarizing beamsplitter, the second rotatory component and the third polarizing beamsplitter in sequence and then the combined light beam exits, the second rotatory component rotates 90° for the light beam entering in the opposite direction.

2. The two-stage optical isolator of claim 1, wherein, The first polarizing beamsplitter has the first beamsplitting film and the second beamsplitting film arranged in parallel to each other, the transmission axis of the first beamsplitting film and the second beamsplitting film is S-axis, the S-polarized light beam can exit after passing through the first beamsplitting film, and the P-polarized light beam reflects through the first beamsplitting film and the second beamsplitting film in sequence and then exits parallelly with the P-polarized light beam.

3. The two-stage optical isolator of claim 2, wherein, The angle between the first beamsplitting film, the second beamsplitting film and the incident light beam is 45°.

4. The two-stage optical isolator of claim 2, wherein, The second polarizing beamsplitter has the third beamsplitting film and the fourth beamsplitting film arranged perpendicularly to each other, the transmission axis of the third beamsplitting film is P-axis, and the transmission axis of the fourth beamsplitting film is S-axis.

5. The two-stage optical isolator of claim 4, wherein the first stage optical isolator is a Faraday isolator and the second stage optical isolator is a polarization beam splitter. The third beamsplitting film is parallel to the first beamsplitting film.

6. The two-stage optical isolator of claim 1, wherein, The third polarizing beamsplitter has the fifth beamsplitting film and the sixth beamsplitting film arranged in parallel to each other, the transmission axis of the fifth beamsplitting film and the sixth beamsplitting film is S-axis, the S-polarized light beam can pass through the sixth beamsplitting film, and the P-polarized light beam passes through the fifth beamsplitting film and the sixth beamsplitting film in sequence and then combines with the S-polarized light beam to exit.

7. The two-stage optical isolator of claim 6, wherein, The angle between the fifth beamsplitting film, the sixth beamsplitting film and the incident light beam is 45°.

8. The two-stage optical isolator of claim 1, wherein, The first rotatory component includes the first rotatory sheet and the first magneto-optical crystal sequentially arranged along the light path direction, the first magneto-optical crystal is provided with the first magnet outside, and the P-polarized light beam and the S-polarized light beam are rotated and exchanged in sequence through the first rotatory sheet and the first magneto-optical crystal.

9. The two-stage optical isolator of claim 1, wherein, The second rotatory component includes the second magneto-optical crystal and the second rotatory sheet sequentially arranged along the light path direction, the second magneto-optical crystal is provided with the second magnet outside, and the P-polarized light beam and the S-polarized light beam entering in the opposite direction are rotated and exchanged in sequence through the second magneto-optical crystal and the second rotatory sheet.

10. The two-stage optical isolator of claim 1, wherein, The collimator is arranged at the incident light, the light beam passes through the collimator to collimate and then exits to the first polarizing beamsplitter.

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